Problem with Boolean Difference Overhang
I understand it can take awhile to wrap your head around it.  I create all my 3D printed models using Blender 2.91.  The Boolean operator has been greatly improved using the exact and self options (Although the Fast option will work with this model just as well)

1st) The overhang is just the bottom face. Should print just fine not sure if your printer will require supports for the hole though.

2nd) Animation of doing Boolean - Difference with your object.

3rd) Animation of overhang location and how to find it.

4th) If you want to display the hole during edit mode you have to enable it or apply the modifier)

5th) Exported to slicer note: not sure if your printer will require supports for the hole or not.